Latitudes of the Eastern Ural microcontinent and Magnitogorsk island arc in the Paleozoic Ural Ocean

Research subject. Rocks of the Paleozoic Eastern Ural microcontinent and Magnitogorsk island arc occupy a significant part of the Southern Urals and some part of the Middle Urals. The Western Urals are composed of rocks of the ancient Baltic continent and overthrust oceanic rocks. In the Eastern Urals and Trans-Urals rocks of the accretion complexes, oceanic crust, island arcs, the Eastern Ural microcontinent and the Kazakhstan Paleozoic continent are widespread. Rocks are exposed in the Denisov tectonic zone. The Magnitogorsk simatic Island Arc originated in the Ural Ocean, near the Baltic continent, in the early Devonian, developing from the Emsian to the Famennian. A collision between the Magnitogorsk arc and the Baltic continent occurred in the Famennian century. In the pre-Carboniferous age, the Eastern Ural microcontinent was located in the Ural Ocean. In the Tournaisian period, the Eastern Ural microcontinent accreted with the Baltic continent. The Kazakhstan continental massif was located on the other side of the Ural Ocean. The volcanic belt above the subduction zone was active on the edge of the Kazakhstan continent in the Early–Middle Devonian and in the Early Carboniferous. A subduction under the Baltic and Kazakhstan continents consumed most of the crust of the Ural Ocean by the middle of the Bashkir century. As a result, the Baltic continent (together with the Eastern Ural microcontinent) came into contact with the Kazakhstan continent. The formation of folded orogen began in the Moscow century following the collision of sialic terrains.

Materials and methods. The research was based on the relevant data obtained by several researchers in 2000–2018 on rock paleomagnetism.

Results. The paleolatitudinal positions of the Eastern Ural microcontinent were determined, comprising 5.3 ± 7.4°) in the Middle Ordovician and 8.2 ± 7.2° in the Early–Middle Silurian. The respective paleolatitudinal positions for the Early–Middle Devonian comprised: the Ural margin of the Baltic paleocontinent (7.7 ± 3.7°), the Magnitogorsk island arc (3.2 ± 3.1°) and the Ural margin of the Kazakhstan paleocontinent (20.6 ± 3.8°).

Conclusion. According to the analysed paleomagnetic data, in the Early–Middle Devonian, the distance between the latitudes of the margins of the Baltic and Kazakhstan continents was not less than 600 km provided they were in the same hemisphere, and more than 2,300 km provided they were in different hemispheres. The convergence of the terrains was associated with the subduction of the Ural Ocean crust before its closure, which occurred in the Tournaisian century.

1. Atlas litologo-paleogeograficheskikh, strukturnykh, palinspasticheskikh i geoekologicheskikh kart Tsentral’noi Evrazii [Atlas of lithological-paleogeographic, structural, palinspastic and geoekologicalal maps of Central Eurasia]. (2002) Almaty, TsGO Publ., 72 p.

2. Antsygin N.Ya. (1985) To the Ordovician stratigraphy on the eastern slope of the Urals. Problemy geologii dokembriya i nizhnego paleozoya Urala [Problems of Precambrian and the Lower Paleozoic geology of the of the Urals]. Moscow, Geolfond of the RSFSR Publ., 68-86. (In Russian)

3. Burtman V.S., Dvorova A.V. (2018) Kazakhstan and Tarim microcontinents on the Devonian paleotectonic reconstructions. Litosfera, 18(2), 314-321. DOI: 10.24930/1681-9004-2018-18-2-314-321 (In Russian)

4. Burtman V.S., Dvorova A.V. (2019) Kokchetau-Issykkul terrain of the Kazakhstan Paleozoic continent and the Ordovician latitude of the continent. Litosfera, 19(4), 519–532. DOI: 10.24930/1681-9004-2019-19-4-519-532. (In Russian)

5. Burtman V.S., Gurary G.Z., Dvorova A.V. (2003) Position of microcontinents in the Northern Tien Shan and the Eastern Urals in the Ordovician and Silurian from paleomagnetic data. Geotectonics, 37(5) 352-367.

6. Burtman V.S., Gurarii G.Z., Dvorova A.V., Kuznetsov N.B., Shipunov S.V. (2000) The Uralian Paleoocean in the Devonian (as inferred from paleomagnetic data). Geotectonics, 34(5), 397-406.

7. Chuvashov B.I., Shuiskii V.P. (2003) Early Devonian biota of carbonate platforms of the east of the Russian Platform, the Ural Mobile Belt and Western Siberia (stratigraphic, biogeographic and paleotectonic significance). Litosfera, (2), 3-27. (In Russian)

8. Fershtater G. B., Krasnobaev A. A., Bea F., Montero P., Borodina N.S. (2007) Geodynamic settings and history of Paleozoic intrusive magmatism of the Middle and Southern Urals (based on the results of zircon dating)). Geotektonika, (6), 52-77. (In Russian)

9. Filippova I.B., Bush V.A. (2001) Middle Paleozoic subduction belts: The leading factor in the formation of the Central Asian fold-and-thrust belt. Russ. J. Earth Sci., 3(6), 1-36.

10. Golovanova I.V., Danukalov K.N., Puchkov V.N., Kosarev A.M., Sal’manova R.Yu. (2018) Paleomagnetic studies in the Devonian and Carboniferous rocks of the Southern Urals: an independent test of the concept of a collision between the Magnitogorsk island arc and the passive edge of the Lavrusia continent. Dokl. Akad. Nauk, 482(1), 64-67. (In Russian)

11. Khain V.E. (2001) Tektonika kontinentov i okeanov [Tectonics of continents and oceans]. Moscow, Nauchnyi Mir Publ., 606 p. (In Russian)

12. Kosarev A.M., Puchkov V.N., Svetlakova A.N. (2001) Geological interpretation of the seismic profile of Uralseys (East domain). Glubinnoe stroenie i geodinamika Yuzhnogo Urala (proekt Uralseys) [The deep structure and geodynamics of the Southern Urals (Uralseys project)]. Tver, GERS Publ., 165-171. (In Russian)

13. Kurenkov S.A., Didenko A.N., Simonov V.A., Lubnina N.V. (2005) Geodynamic conditions for the formation of paleo-spreading complexes of the Ural-Mongolian belt. Ocherki po regional’noi tektonike. T. 2 [Essays on regional tectonics, V. 2]. Moscow, Nauka Publ., 201-247. (In Russian)

14. Kurchavov A.M. (2004) Formation series of orogenic volcanic belts and their significance for paleoreconstructions. Geol. Geofiz., 45(12), 1418-1426. (In Russian)

15. Litvin P.A., Mamaev N.F. (1961) Ob”yasnitel’naya zapiska k geologicheskoi karte SSSR, list N-41-XXXIII [Explanatory note to the geological map of the USSR, sheet N41-XXXIII]. Moscow, Gosgeoltekhizdat Publ., 70 p. (In Russian)

16. Maslov V.P., Artyushkova O.V., Baryshev V.N. (1984) Stratigrafiya rudovmeshchayushchikh devonskikh otlozhenii Sibaiskogo raiona [Stratigraphy of the Ore Devonian deposits of the Sibay district]. Ufa, IG BFAN SSSR, 100 p. (In Russian)

17. Necheukhin V.M., Volchek E.N. (2015) Tectonic-geodynamic zoning of the Ural-Timan paleoasian segment of Eurasia. Litosfera, (6), 5-25. (In Russian)

18. Necheukhin V.M., Krasnobaev A.A., Sokolov V.B. (2000) Terranes of the ancient continental crust in accretion-collision structures of the Urals. Dokl. Akad. Nauk, 370(5), 655-657. (In Russian)

19. Perfil’ev A.S. (1979) Formirovanie zemnoi kory Ural’skoi evgeosinklinali [Formation of the Earth’s crust of the Ural eugeоsyncline]. Moscow, Nauka Publ., 188 p. (In Russian)

20. Puchkov V.N. (2000) Paleogeodinamika Yuzhnogo i Srednego Urala [Paleogeodynamics of the Southern and Middle Urals]. Ufa, Dauria Publ., 146 p. (In Russian)

21. Puchkov V.N. (2010) Geologiya Urala i Priural’ya [Geology of the Urals and Cis-Urals (modern stratigraphy, tectonics, geodynavics and metallogeny data)]. Ufa, DesignPoligraphServis Publ., 280 p. (In Russian)

22. Ruzhentsev S.V., Samygin G.S. (2004) Structure and geological development of the junction area of the East European Platform and the Southern Urals. Geotektonika, (4), 20-44. (In Russian)

23. Samygin S.G., Burtman V.S. (2009) Tectonics of the Ural Paleozoides in comparison with the Tien Shan. Geotectonics, 43(2), 133-151. DOI: 10.1134/S0016852109020058

24. Samygin G.S., Ruzhentsev S.V. (2003) Ural Paleoocean: a model of inherited development. Dokl. Akad. Nauk, 392(2), 226-229. (In Russian)

25. Samygin S.G., Kheraskova T.N., Kurchavov A.M. (2015) Tectonic development of Kazakhstan and the Tien Shan in the Neoproterozoic and Early-Middle Paleozoic. Geotektonika, (3), 66-92. (In Russian)

26. Shurygina M.V., Militsyna V.S. (1996) Silurian deposits along the Istok and Bagaryak rivers in the area of Kamensk-Uralsk in the east of the Middle Urals. Materialy po stratigrafii i paleontologii Urala, 1 [Materials on stratigraphy and paleontology of the Urals, 1]. Ekaterinburg, UB RAS, 25-37.

27. Smirnov V.N., Borozdina G.N., Desyatnichenko L.I., Ivanov K.C., Medvedeva T.Yu., Fadeicheva I.F. (2006) On the time of disclosure of the Ural paleoocean. Geol. Geofiz., 47(6), 755-761. (In Russian)

28. Svyazhina I.A., Petrov G.A. (2011) Migration of terranes of the Ural mobile belt and Paleozoic accretion events on the Ural margin of the East European continent. Litosfera, (6), 3-13. (In Russian)

29. Svyazhina I.A., Petrov G.A., Slobodchikov E.A. (2008) Paleomagnetism, tectonics and geodynamics of the Paleozoic of the Middle Ural fragment of the East Ural megazone. Litosfera, (4), 22-34. (In Russian)

30. Tevelev A.V., Kosheleva I.A. (2002) Geologicheskoe stroenie i istoriya razvitiya Yuzhnogo Urala [Geological structure and history of the development of the Southern Urals]. Moscow, MGU Publishing House, 120 p. (In Russian)

31. Tevelev A.V., Kosheleva I.A., Popov V.S., Kuznetsov I.E., Osipova T.A., Pravikova N.V., Vostretsova E.S., Gustova A.S. (2006) Paleozoidy zony sochleneniya Vostochnogo Urala i Zaural’ya [Paleozoids of the junction zone of the Eastern Urals and Trans-Urals]. Moscow, MGU Publishing House, 300 p. (In Russian)

32. Torsvik T.H., Van der Voo R., Preeden U., MacNiocaill C., Steinberger B., Doubrovine P.V., Hinsbergen D.J.J., Domeir M., Gaina C., Tohver E., Meert J.G., McCausland P.J.A., Cocks R.M. (2012) Phanerozoic polar wander, palaeogeography and dynamics. Earth Sci. Rev., 114, 325-368.

33. Windley B.F., Alexeiev D., Xiao W., Kroner A., Badarch G. (2007) Tectonic models for accretion of the Central Asian Orogenic Belt. J. Geol. Soc. London, 164, 31-47.